Faster returns on ‘leaf economics’ and different biogeochemical niche in invasive compared with native plant species

Abstract

Plant-invasive success is one of the most important current global changes in the biosphere. To understand which factors explain such success, we compared the foliar traits of 41 native and 47 alien-invasive plant species in Oahu Island (Hawaii), a location with a highly endemic flora that has evolved in isolation and is currently vulnerable to invasions by exotic plant species. Foliar traits, which in most cases presented significant phylogenetic signal, i.e. closely related species tended to resemble each other due to shared ancestry, separated invasive from native species. Invasive species had lower leaf mass per area and enhanced capacities in terms of productivity (photosynthetic capacity) and nutrient capture both of macro-(N, P, K) and microelements (Fe, Ni, Cu and Zn). All these differences remain highly significant after removing the effects of phylogenetic history. Alien-invasive species did not show higher efficiency at using limiting nutrient resources, but they got faster leaf economics returns and occupied a different biogeochemical niche, which helps to explain the success of invasive plants and suggests that potential increases in soil nutrient availability might favor further invasive plant success.

Cat's claw creeper vine, Macfadyena unguis-cati (Bignoniaceae), invasion impacts: comparative leaf nutrient content and effects on soil physicochemical properties

“…The trend of higher leaf-nutrient load (especially N, P and K) in exotic vines M. unguis-cati and P. suberosa (Table 3) is linked to the preference of invasive plant species for disturbed habitats commonly associated with high pulses of nutrient input (Davis et al 2000). As in our study, Penuelas et al (2010) found that several invasive species had enhanced capacities in terms of productivity and nutrient capture both of macro-(N, P, K) and micro elements (Fe, Ni, Cu and Zn) and suggested that potential increases in soil nutrient availability might favour further success of invasive plants.…”

“…M. unguis-cati leaves also had higher concentrations of potentially toxic ions (Al, Cd, Co and Cu) than the concentrations present in leaves of non-invasive species (Table 3), indicating that M. unguis-cati may more readily take up metal contaminants from the soil than do native species. Penuelas et al (2010), in a general survey of leaf economics of invasives and biogeochemical niche, alluded to the relatively higher abundance of these potentially toxic trace elements in many invasive plant organs and suggested that the cycling of these elements could be accelerated in invasive alien-dominated ecosystems. However, the influence of M. unguis-cati in altering the soil's biogeochemical cycle appeared not to be as dramatic as that of Lantana camara, known to decrease the concentrations of a greater number of heavy and/or toxic metals such as Fe, Cu, Mn and S (see Osunkoya and Perrett 2011).…”

“…Recent work and reviews have concluded that, on average, alien invasive plants increase nutrient pools and fluxes in novel ecosystems (e.g. Dassonville et al 2008;Osunkoya and Perrett 2011;Penuelas et al 2010). However, high variability both in the magnitude and direction of the response to invasion has been observed (Ehrenfeld 2003;Liao et al 2008;.…”

“…A plant community becomes more susceptible to invasion with increasing availability of resources (Davis et al 2000;Osunkoya et al 2010a;Penuelas et al 2010). For example, the position of riparian forests as edges between terrestrial and aquatic systems tends to enhance fluxes of energy and species turnover, with a high degree of disturbance as a result of water-level fluctuations (Planty-Tabacchi et al 1996;Naiman and Decamps 1997).…”

“…Thus, the impacts of an invasive species are often context-specific, depending on the invader's characteristics relative to those of the system into which it enters. Factors influencing level impact of include the degree of difference in key traits between the invasive and native species, and specifics of the landscape setting such as habitat type, initial site condition, soil characteristics and moisture regime (Ehrenfeld 2003;Dassonville et al 2008;Penuelas et al 2010;.…”